1. Field of the Invention
The present invention relates to a method of manufacturing a three-dimensionally shaped object in which the shaped object is obtained by successively laminating hardened layers of hardened powder material.
2. Description of the Related Art
A method as shown in FIGS. 50A and 50B of manufacturing a three-dimensional object by successively laminating hardened layers 102 of hardened powder material 101 is well known. This is disclosed in Japanese Patent No. 2620353 as a xe2x80x9cMethod of manufacturing parts by selective sintering.xe2x80x9d According to this Patent, the powder material 101, which is an organic material such as a resin or an inorganic material such as a metal, is first accumulated and then hardened to form a hardened layer 102 by irradiating thereon an optical beam (laser beam 112) such as a laser or directional energy beam. The hardened layers 102 thus obtained are laminated one above another to form a three-dimensional object.
In this case, as shown in FIG. 50A, the powder material 101 is supplied from a hopper 129 to an enclosing structure 130, and as shown in FIG. 50B, a laser beam 112 is selectively irradiated onto a predetermined position. This is repeatedly carried out to form a laminate of the hardened layers 102. The laser beam 112 is emitted from a laser head 131 and is operated in such a way that the direction of its path is altered by a scanning system 133 including a prism 132 so that a predetermined position on the powder material 101 of the uppermost layer within the enclosing structure 130 is selectively irradiated. Accordingly, a complex shaped object can be manufactured comparatively easily.
In the above-described prior art, however, the packing density of the powder material 101 is low and, hence, the density after irradiation and hardening does not become 100%. For this reason, there are problems in that the strength of the manufactured shaped object is weaker by comparison with the essential mechanical strength of the material. There are additional problems in that although the laser beam 112 must be scanned to form the hardened layers 102, the shaping time becomes long because the amount of scanning data within the contour lines of the shaped object is large. There are further problems in that, because the powder material 101 contracts when it is hardened, the hardened layers 102 are deformed and a shaped object of satisfactory precision cannot be manufactured.
The present invention has been developed to overcome the above-described disadvantages.
It is accordingly an objective of the present invention to provide a method of manufacturing a three-dimensional object which is capable of easily manufacturing a shaped object of high strength and high precision, even if the shape thereof is complex.
In accomplishing the above and other objectives, the method according to the present invention is characterized by: (a) filling a powder material around a core so as to form a layer of powder material; (b) selectively irradiating a beam on the layer of powder material to form a hardened layer united with the core, and (c) repeating the steps (a) and (b) to form a plurality of hardened layers around the core.
According to this method, if the core is so formed as to have a high density and a high strength, the shaped object has a high strength as a whole. Moreover, only the powder material in the outer region in the proximity of the core needs to be successively hardened to form a laminated structure, and the amount of scanning data, for the scanning of the beam which affords the hardening at this time, is reduced within the contour lines of the shaped object. As a result, the scanning time is shortened and, even if the shape is complex, the shaping time can be also shortened. In addition, because the amount of powder material to be hardened is reduced, distortion or deformation due to contraction during hardening is prevented and a high precision shaped object can be manufactured.
Furthermore, by lowering the core by a dimension equivalent to the thickness of each hardened layer, the hardened layers are successively laminated around the core. Also, the powder material can be filled easily after each hardening, and the distance setting and the like of the beam to be irradiated thereon is also easy.
The core is made up of a plurality of sheet materials laminated one above another that are united together before the steps (a) and (b), and each of the sheet materials is an organic material or an inorganic material. Because the core is integrated in advance, it can be easily made even if the shaped object has a complicated shape.
Alternatively, each of the plurality of sheet materials is laminated before the step (a). By so doing, there is no need for the sheet materials to be integrally laminated in advance, and the core can be formed simply by successively laminating the sheet materials prior to the formation of the hardened layers. Also, the core forms no obstruction to the filling of the powder material.
Advantageously, each of the plurality of sheet materials has a through-hole, in which the powder material is filled and hardened to unite neighboring sheet materials. In this case in particular, the sheet materials are joined by the hardening of the powder materials filled into the through-holes, so the joining strength between the sheet materials is enhanced and the distortion of the sheet materials due to heat effects during hardening of the powder material is prevented, resulting in a shaped object of higher density and higher precision. Furthermore, the sheet materials can be appropriately positioned with each other without lateral offsetting.
The through hole can be so formed as to extend through all of the plurality of sheet materials. The through- hole may be inclined.
Each sheet material may be coated with a powder material, wherein a beam is irradiated thereon to unite neighboring sheet materials, resulting in a shaped object of high strength.
The powder material may have a melting point lower than that of the sheet materials.
Each sheet material may have an independent area connected thereto via a plurality of connecting portions, which are removed during or after the shaping.
When a box-shaped object is manufactured, the powder material is filled in a space formed at an edge portion of each sheet material.
It is preferred that the plurality of sheet materials be appropriately positioned by at least one positioning member. The positioning member is a movable member driven by a separate device, or is formed on at least one of the plurality of sheet materials. Alternatively, the positioning member is formed by irradiating a beam on a powder material coated on the at least one of the plurality of sheet materials. Again alternatively, the plurality of sheet materials are appropriately positioned by protrusions formed thereon. Each of the plurality of sheet materials may have a positioning piece integrally formed therewith, which is brought into contact with a separate positioning member.
All the sheet materials do not have the same thickness, that is, the plurality of sheet materials may have different thickness. In this case, the thickness of the sheet materials are set to be thick at positions where the inclination of the outer side surface of the core is steep and to be thin at positions where the inclination is gentle. Accordingly, the level difference generated at the edges of the sheet materials can be reduced, making it possible to smoothly finish the surface of the shaped object.
A solidified powder layer may be interposed between neighboring sheet materials. In this case in particular, even if the laminated surface of the sheet materials has a complicated shape, a shaped object having a fine and complicated shape can be easily manufactured by arranging the solidified powder layer in position between the neighboring sheet materials.
The layer of powder material filled around each sheet material may have a tapered upper surface formed by vibration. By so doing, smooth-finishing of the surface of the shaped object can be achieved. Moreover, when polishing is performed, the amount to be removed is reduced, making it possible to reduce the finishing time.
The core and the powder material may be made of different materials. In this case, shaped objects having a high surface hardness such, for example, as cutters, grinding tools and the like can be easily manufactured.
Alternatively, paper, plastic resin, aluminum or the like, which has a melting point lower than that of the powder material, may be used for the core, while iron- or copper-based powder may be used for the powder material. Because the core has a melting point lower than that of the powder material, a beam having an energy density lower than that of the beam used to harden the powder material can be used to firmly join neighboring sheet materials, thereby preventing poor adhesion between the sheet materials.
In this case, the core is removed from the plurality of hardened layers, thereby forming a cavity therein. This cavity can be used for, for example, a water or air passage for cooling use. Alternatively, amcolten or fluidic material is filled in the cavity. If copper or aluminum is filled in the hollowed object, the thermal conductivity thereof is increased. Also, a heater or a foaming object can be made by filling the hollowed object with an electric resistance material or concrete, respectively. In addition, a shaped object having heat storage effects can be made by filling a high-polymer resin therein.
Alternatively, the core is made of a conductive material, while the powder material is made of an insulating material.
By this construction, three-dimensional circuits can be simply made within a reduced period of time. Furthermore, a cooling pipe or a heater can be embedded in the hardened layers or in the conductive material.